feat: per-row start button on runnable flows (0.21.2)

Flows without missing modules get a play button in the list that
opens them directly on the Run tab - one click from the list to
entering inputs and starting a run. Rows with missing modules keep
the install badge as their single actionable path.

Signed-off-by: flemming-it <sf@flemming.it>

lib/src/flow_editor_page.dart

@@ -289,6 +289,17 @@ class _FlowEditorPageState extends State<FlowEditorPage>
     return files;
   }
 
+  /// Row-level start: open the flow and land directly on the Run
+  /// tab, where inputs + the start button live. One click from the
+  /// list to running a flow.
+  Future<void> _startFile(_FlowFile f) async {
+    await _openFile(f);
+    if (!mounted) return;
+    if (_controller.analyzerErrorCount == 0) {
+      _tabs.animateTo(2);
+    }
+  }
+
   Future<void> _openByName(String name) async {
     final path = '${_defaultFlowsDir()}/$name.yaml';
     final file = File(path);
@@ -551,6 +562,7 @@ outputs:
                     ),
                     onOpen: _openFile,
                     onRefresh: _refreshFiles,
+                    onStart: _startFile,
                     onInstallMissing: widget.onInstallCapability == null
                         ? null
                         : _installMissingCaps,
@@ -1218,6 +1230,11 @@ class _FileList extends StatelessWidget {
   final void Function(_FlowFile) onOpen;
   final VoidCallback onRefresh;
 
+  /// Open the flow directly on the Run tab — the per-row start
+  /// affordance the usertest asked for. Rows with missing modules
+  /// don't offer it (they can't run yet).
+  final void Function(_FlowFile) onStart;
+
   /// Install the listed missing capabilities. `null` when the
   /// host wired no install handler — the warning badge still
   /// renders, just without the one-click action.
@@ -1230,6 +1247,7 @@ class _FileList extends StatelessWidget {
     required this.installedNames,
     required this.onOpen,
     required this.onRefresh,
+    required this.onStart,
     required this.onInstallMissing,
   });
 
@@ -1401,6 +1419,25 @@ class _FileList extends StatelessWidget {
                         ],
                       ),
                     ),
+                    // Per-row start: one click from the list to the
+                    // Run tab. Hidden while modules are missing —
+                    // the install badge is the actionable path then.
+                    if (missing.isEmpty)
+                      IconButton(
+                        onPressed: () => onStart(f),
+                        tooltip: strings.listStartTooltip,
+                        icon: Icon(
+                          Icons.play_arrow_rounded,
+                          size: 20,
+                          color: theme.colorScheme.primary,
+                        ),
+                        visualDensity: VisualDensity.compact,
+                        padding: EdgeInsets.zero,
+                        constraints: const BoxConstraints(
+                          minWidth: 32,
+                          minHeight: 32,
+                        ),
+                      ),
                   ],
                 ),
               ),